Gas-dissolving device and gas-dissolving method

A gas dissolving device attachable to a water tank, comprising:

• a chamber,
• a tube, and
• a diaphragm pump that, when attached to the water tank, suctions water from the water tank, imparts the water with hydrogen as hydrogen bubbles to generate hydrogen water, supplies the water, the hydrogen bubbles, and the hydrogen water to the chamber under a pressure of Y MPa, said chamber having an inlet, an upper portion in which hydrogen separated from the hydrogen water accumulates, and a lower portion having the tube connected thereto, said tube having an inside diameter of X mm, an outlet, and a pressure adjusting unit near the outlet, and the value of X/Y is 1.00 to 12.00, and
• wherein the hydrogen water is discharged from the lower portion of the chamber through the tube by laminar flow and thereby pressure variation in the chamber is prevented and the hydrogen water is maintained in a saturated state in the chamber.